SS Hex Bolt or Screws are usually full threaded or partial/half threaded.
Generally they are Hexagonal or Heavy Hexagonal Bolts/Screws where the difference is determined through their Hex head size. As the dimension of Heavy Hex across flat is more than the hex across flat, more bearing area will be covered by Heavy Hex Bolt and hence having high strength or more bearing pressure.

Different sizes, material, designs and types are available.